I implemented all the changes we talked about in our last meeting:
- Instead of manipulating sapStressThreshold we now manipulate height growth (simulated via the browsing module, same browsing probability for all species)
- New modification levels: size x c(1,2,5,10), frequency x c(1,2,5,10), fecundity x c(1,1/2,1/5,1/10), browsing pressure x c(1,2,5,10)
- New output: dynamic stand in year 2020, 2050 and 2100
- Severity for all agents set to 90 % (and 100 for sapling during fire)
- Fire can only burn cells with a fuel load > 500 kg/ha
I then ran a complete suite of simulations for Berchtesgaden (4 patch size levels * 4 disturbance frequency levels * 4 fecundity levels * 4 browsing levels * 2 climate scenarios * 1 rep = 512 runs)
Here are the results!
Short recap of our indicators:
Structure: basal area decreased by >50 % from reference
Composition: dominant species changed from reference
Remaining forest: stem density dropped below 50 trees/ha
Reference: value under reference conditions (no process modification + baseline climate), calculated for each RU and each year
Structure changes very quickly until mid of century, then recovers under hot-dry climate, and continues to change under baseline climate, lowest value ~15%
Composition changes continuously for both baseline and hot-dry conditions, lowest value ~50%
Very little forest loss, lowest value ~90 %
Values in year 2100
All processes play a role in structural change, disturbance processes (first row) however seem to have a bigger impact (relatively little change at modification level 1)
More structural change under baseline climate
Values in year 2100
Mainly the disturbance processes (first row) seem to have an impact on compositional change (relatively little change at modification level 1) - especially under modification level 10
Compositional change similar under baseline and hot-dry climate
Values in year 2100
Basically only regeneration processes (second row) seem to have an impact on forest loss (relatively little change at modification level 1)
More forest loss under baseline climate
Species composition remained relatively stable under reference conditions (= no process modification, first row) and differences between the climate scenarios were small. (Interesting! I would have expected spruce to decrease due to higher temperatures under hot-dry but it still seems to do fairly well without climate change-mediated disturbance change)
Under the most extreme scenario (size * 10 + frequency * 10 + fecundity/10 + browsing * 10, second row) spruce decreased while all other species increased - especially larch (makes sense, it should be able to do very well in all those disturbance patches). Fir also benefited from the increase in disturbances:
Short recap of our indicators:
Structure: basal area decreased by >50 % from reference
Composition: dominant species changed from reference
Remaining forest: stem density dropped below 50 trees/ha
Reference: value under reference conditions (no process modification + baseline climate), calculated for each RU and each year
Structure changes very quickly until mid of century, then recovers under hot-dry climate, and continues to change under baseline climate, lowest value ~15%
Composition changes continuously for both baseline and hot-dry conditions, lowest value ~50%
Very little forest loss, lowest value ~90 %
Values in year 2100
Basically only regneration processes (second row) seem to have an impact on structural change (relatively little change at modification level 1)
Generally more structural change under hot-dry climate
Values in year 2100
Mainly climatic processes (colors) seem to have an impact on compositional change
Compositional change much higher under hot-dry climate
Values in year 2100
Basically only regeneration processes (second row) seem to have an impact on forest loss (relatively little change at modification level 1) - especially browsing
More forest loss under hot-dry climate
Species composition remained relatively stable under reference conditions (= no process modification, first row). Differences between the climate scenarios started showing in the later half of the century.
Under hot-dry conditions Betula ermanii decreased most strongly while Acer mono and Kalopanax septemlobus increased in turn. Differences between the process modification scenarios were very small:
~ the end (for now…) ~